On Wed, 2009-03-11 at 13:50 -0700, Grant Lowe wrote: > Hi Eric, > > Thanks for the quick response. Then on hostB, the new LUN will need the same > amount of disk space for the pool, as on hostA, if I'm understanding you > correctly. Correct? Thanks!
I'm assuming you're referring to my second case, where you don't bother to 'import'/'export' and single LUN, and just use the 'send'/'receive' option. HostB's zpool only needs to have enough space to handle the snapshot size. You can of course delete a snapshot on either host after it's taken, so you may not need to keep all snapshots around on both hosts. So, let's say this happens: pool on hostA is 2TB, with 1TB of active data, and a typical snapshot of 100GB. Which means you can keep around 10 snapshots on hostA. On hostB, you need a zpool of 1TB for the 'live' data, plus 100GB extra to store an incoming snapshot, but once you've received the snapshot, you can delete any older snapshot, so you really only need 1.1TB on hostB. Unless, of course, you want to keep the older snapshots. For old timer's sake, compare 'zfs send' and 'zfs'receive' to 'ufsdump' and 'ufsrestore' (respectively) for their utility. -Erik > > > ----- Original Message ---- > From: Erik Trimble <[email protected]> > To: Grant Lowe <[email protected]> > Cc: [email protected] > Sent: Wednesday, March 11, 2009 1:42:06 PM > Subject: Re: [zfs-discuss] ZFS on a SAN > > I'm not 100% sure what your question here is, but let me give you a > (hopefully) complete answer: > > (1) ZFS is NOT a clustered file system, in the sense that it is NOT > possible for two hosts to have the same LUN mounted at the same time, > even if both are hooked to a SAN and can normally see that LUN. > > (2) ZFS can do failover, however. If you have a LUN from a SAN on > hostA, create a ZFS pool in it, and use as normal. Should you with to > failover the LUN to hostB, you need to do a 'zpool export <zpool>' on > hostA, then 'zpool import <zpool>' on hostB. If hostA has been lost > completely (hung/died/etc) and you are unable to do an 'export' on it, > you can force the import on hostB via 'zpool import -f <zpool>' > > > ZFS requires that you import/export entire POOLS, not just filesystems. > So, given what you seem to want, I'd recommend this: > > On the SAN, create (2) LUNs - one for your primary data, and one for > your snapshots/backups. > > On hostA, create a zpool on the primary data LUN (call it zpool A), and > another zpool on the backup LUN (zpool B). Take snapshots on A, then > use 'zfs send' and 'zfs receive' to copy the clone/snapshot over to > zpool B. then 'zpool export B' > > On hostB, import the snapshot pool: 'zfs import B' > > > > It might just be as easy to have two independent zpools on each host, > and just do a 'zfs send' on hostA, and 'zfs receive' on hostB to copy > the snapshot/clone over the wire. > > -Erik > > > > On Wed, 2009-03-11 at 13:18 -0700, Grant Lowe wrote: > > Hi All, > > > > I'm new on ZFS, so I hope this isn't too basic a question. I have a host > > where I setup ZFS. The Oracle DBAs did their thing and I know have a > > number of ZFS datasets with their respective clones and snapshots on > > serverA. I want to export some of the clones to serverB. Do I need to > > zone serverB to see the same LUNs as serverA? Or does it have to have > > preexisting, empty LUNs to import the clones? Please help. Thanks. > > > > _______________________________________________ > > zfs-discuss mailing list > > [email protected] > > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss -- Erik Trimble Java System Support Mailstop: usca22-123 Phone: x17195 Santa Clara, CA Timezone: US/Pacific (GMT-0800) _______________________________________________ zfs-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
